I. Technical Field
The present invention relates to a method for transferring substrates including glass substrates such as a liquid-crystal display substrate (LCD substrate) or a plasma display substrate (PDP substrate), and a component mounting equipment for mounting components including electronic components such as IC chips or various semiconductor devices onto these types of substrate.
II. Description of the Related Art
An example of a conventional component mounting equipment is disclosed in Japanese Patent Application Laid-Open Publication No. 2001-228452. Referring to FIG. 20, a reference numeral “1” denotes a substrate stage for holding a substrate 2. Suction holes (not illustrated) are formed in the substrate stage 1 which is a rigid body and a lower side of the substrate 2 is held by suction force acting through the suction holes. Further, a reference numeral “3” denotes a substrate transfer apparatus that transfers the substrate 2 and delivers the substrate 2 to and from the substrate stage 1. The substrate transfer apparatus 3 has a pair of support arms 4A and 4B which extend in a direction orthogonal to a direction of transferring of substrate 1 indicated by an arrow “A1”. These support arms 4A and 4B have suction pads 5 for holding the lower side of the substrate 2. The substrate stage 1 moves the substrate 2 transferred from the substrate transfer apparatus 3 at a substrate taking-over potion shown in the figure to a working section which is not illustrated (Refer to an arrow “A2”). In the working sections, various mounting operations such as supply of a binding material to the substrate 2, pre-press bonding of components, and final-press bonding of these components are executed. Further, the substrate stage 1 moves from the working section to the substrate taking-over position and places the substrate 2 onto the substrate transfer apparatus 3 (Refer to an arrow “A3”). Such component mounting equipment is also disclosed in International Publication WO01/58233.
Recently, the substrates to which mounting operations are carried out by such component mounting equipments have tended to increase in size. For example, the size of the substrate is approximately on the order of 13 to 15 inches for notebook-type PC displays, 17 to 21 inches for monitor displays, and 15 to 20 inches for television displays.
In the case of the component mounting equipment shown in FIG. 20, as indicated by the arrows “A2” and “A3”, either when the substrate stage 1 moves from the working section to the substrate taking-over position or when the substrate stage 1 moves from the substrate taking-over position to the working section, the substrate stage 1 needs to move not only along the transfer direction “A1” of the substrate but also in a direction orthogonal to the transfer direction “A1” for avoiding interference with the support arms 4A and 4B. Due to that movements in these two directions are required, efficient delivery of the substrate between the substrate stage and the substrate transfer apparatus at the substrate taking-over position can not be achieved. Particularly, it is difficult to efficiently move the above-mentioned large size substrate in these two directions.
Further, the necessity of that the substrate stage moves in the direction orthogonal to the transfer direction “A1” of the substrate for delivering the substrate to the substrate transfer apparatus requires increasing the dimensions of the component mounting equipment in the orthogonal direction (the dimension in a depth direction) in order to secure a moving area. The increased dimension in the depth direction increases time necessary for transferring the substrate within the component mounting equipment and also decreases maintenanceability of the component mounting equipment. Particularly, when the substrate is large as mentioned above, the increase in size of the component mounting equipment for securing the moving area is significant.
Furthermore, large warpage can be readily generated for the large size substrate comparing with a small substrate. When the substrate 2 transferred from the substrate transfer apparatus 3 to the substrate stage 1 is warped and has decreased flatness, a positional shift of the substrate 2 is readily produced upon delivery of the substrate 2. The positional shift of the substrate during the delivery can lower operational accuracy at the working section. For example, the positional shift of the substrate during delivery can lower accuracy of mounting position when the pre-press bonding is executed. Further, the warped substrate causes air leakage which extends time necessary for the suction force to rise to an efficient value, resulting in tact loss.